Nonequilibrium Diffusion in Zeolites due to Deterministic Hamiltonian Chaos

We show that diffusionlike transport of a spherical sorbate molecule through a zeolite crystal can be driven by deterministic chaos instead of thermal stochastic noise when the sorbate and crystal do not equilibrate. Using a random-phase approximation for the resulting Arnold diffusion and a boundary-layer analysis of the quasisteady Fokker-Planck equation, we estimate the effective diffusivity to scale as $\sqrt{T}$ for an axisymmetric, single-pore zeolite with a harmonic radial potential, in contrast to the Arrhenius temperature dependence of high-barrier, noise-driven transport of near-equilibrium diffusion.